Chlamydia Trachomatis

Home , Borrelia recurrentis, Chlamydia psittaci, Chlamydophila

陳炳宏老師 [email protected] 校內分機2676 http://allergy.kmu.edu.tw

M I C R O B I O L O G Y WITH DISEASES BY TAXONOMY, THIRD EDITION

• Understand the characteristics of clinically important bacteria – Rickettsias – Clamydias – Spirochetes – Pathogenic Vibrios

• Extremely small • Appear almost wall-less due to small amount of peptidoglycan present • Obligate intracellular parasites – Unusual since have functional genes for protein synthesis, ATP production, and reproduction • Four genera cause disease in humans – Rickettsia, Orienta, Ehrlichia, and Anaplasma

• Rickettsia – Transmitted via arthropod vectors – Bacteria live in the cytosol of host cell – Three species cause most human infections – R. rickettsii – R. prowazekii – R. typhi

Hematoxylin and eosin stain

• Rickettsia – Rickettsia rickettsii – Causes Rocky Mountain spotted fever – Most severe and common rickettsial illness – Hard ticks transmit among humans and rodents – Most infected individuals develop rash on trunk and appendages – Approximately 5% of patients die – Prevention involves avoiding ticks

• Rickettsia – Rickettsia prowazekii – Causes epidemic typhus 流行性斑疹傷寒 – Human body louse transmits bacteria to humans – Humans are primary host of R. prowazekii – Occurs in crowded, unsanitary conditions – Prevent with good personal hygiene – Vaccine available for high-risk populations

• Rickettsia – Rickettsia typhi – Causes murine typhus (endemic typhus) 地方性斑疹傷寒 – Fleas transmit bacteria among animal hosts and humans – Disease is not usually fatal – Most often seen in southern United States – Endemic in every continent except Antarctica – Prevent by avoiding the arthropod vectors

• Orienta 東方體屬 – Formerly classified in the genus Rickettsia – Mites are the reservoir and vector of Orienta – Transmit bacterium among rodents and humans – O. tsutsugamushi causes scrub typhus 恙蟲病 – Occurs in U.S. among immigrants from endemic areas – Prevent by avoiding exposure to mites

• Ehrlichia and Anaplasma – Cause two emerging diseases in the U.S. – E. chaffeensis – Causes human monocytic ehrlichiosis 單核性埃立克體病 – Anaplasma phagocytophilum – Causes anaplasmosis 無漿體病 – Ticks transmit these bacteria – Three developmental stages in leukocytes – Elementary body, initial body, morula – Prevent by avoiding ticks

• Do not have cell walls – Have two membranes without any peptidoglycan between them • Grow and multiply only within the vesicles of host cells • Have a unique developmental cycle involving two forms – Elementary bodies and reticulate bodies – Both forms can occur within the phagosome of a host cell

• Chlamydia trachomatis 砂眼披衣菌 – Pathogenesis and epidemiology – Has a limited host range – One strain infects mice; all others infect humans – Infects the conjunctiva and various mucous membranes – Enters the body through abrasions and lacerations – Most common reportable sexually transmitted disease in U.S. – Clinical manifestations due to cell destruction and inflammatory response

• Chlamydia trachomatis – Diseases – Sexually transmitted diseases (STD) – Lymphogranuloma venereum 性病淋巴肉芽腫 – Nongonococcal urethritis 非淋菌性尿道炎 – Proctitis 直腸炎 – Trachoma – Ocular disease – Leading cause of nontraumatic blindness in humans – Infection typically occurs during childbirth

• Diagnosis, treatment, and prevention – Diagnosis – Demonstrate bacteria inside cells from the site of infection – Treatment – Antibiotics can be administered for genital and ocular infections – Surgical correction of deformities from trachoma may prevent blindness – Prevention – Abstinence to prevent sexually transmitted infections – Blindness prevented with prompt use of antibacterial agents

• Chlamydophila pneumonia 肺炎披衣菌 – Causes bronchitis, pneumonia, and sinusitis – Most infections don’t require hospitalization – Severe cases can resemble primary atypical pneumonia caused by Mycoplasma pneumoniae – Prevention is difficult because C. pneumoniae is ubiquitous

• Chlamydia psittaci 鸚鵡披衣菌 – Causes ornithosis – Disease of bird that can be transmitted to humans – Usually causes flulike symptoms – Rarely nonrespiratory conditions are observed – Individuals who handle animals are at greatest risk of infection – Transmitted via inhalation of aerosols or contact with infected material or a pet bird – Difficult diagnosis since symptoms similar to other respiratory infections

• Thin, tightly coiled, helically shaped bacteria • Moves in a corkscrew fashion through its environment – Thought to enable pathogenic spirochetes to burrow through hosts’ tissues • Three genera cause human disease – Treponema, Borrelia, and Leptospira

• Treponema 梅毒螺旋體, 密螺旋體 – Pathogen of humans only – T. pallidum pallidum is most widespread – Causative agent of syphilis – Syphilis occurs worldwide – Transmission is almost solely via sexual contact – Endemic among sex workers, men who have sex with men, and users of illegal drugs – Can also be spread from an infected mother to her fetus – Can result in fetal death or mental retardation and malformation

Chancre (硬性下疳) on the external genitalia widespread rash

(a) Primary syphilis (b) Secondary syphilis (c) Tertiary syphilis

Gummas (梅毒瘤) on skin, bone, nervous tissues

• Treponema – Diagnosis, treatment, and prevention – Diagnosis – Antibody tests against bacterial antigens – Tertiary syphilis is difficult to diagnose – Treatment – Penicillin is the drug of choice – Ineffective against tertiary syphilis – Prevention – Abstinence and safe sex

• Treponema – Nonvenereal treponemal diseases 非性病梅毒疾病 – Three non-sexually transmitted diseases – Primarily seen in impoverished children in unsanitary conditions – Bejel 非性病梅毒 – T. pallidum endemicum is the causative agent – Pinta 品他病 – T. carateum is the causative agent – Yaws 雅思病 – T. pallidum pertenue is the causative agent

• Borrelia 伯瑞氏疏螺旋體 – Lightly staining, Gram-negative spirochetes – Cause two diseases in humans – Lyme disease 萊姆病 – Relapsing fever 回歸熱

• Borrelia – Lyme disease – Borrelia burgdorferi is the causative agent – Bacteria are transmitted to humans via a tick bite – Hard ticks of the genus Ixodes are the vectors – Tick life cycle important in understanding spread of Lyme disease

• Borrelia – Lyme disease – Shows a broad range of signs and symptoms – Three phases of disease in untreated patients – Expanding red “bull’s-eye” rash occurs at infection site – Neurological symptoms and cardiac dysfunction – Severe arthritis that can last for years – Result of the body’s immune response

• Borrelia – Lyme disease – Increase of cases in the United States – Humans coming in closer association with Borrelia-infected deer ticks – Antimicrobial drugs effectively treat first stage of Lyme disease – Treatment of later stages difficult because symptoms primarily result from the immune response – Prevention is best achieved by avoiding ticks

• Borrelia – Relapsing fever – Louse-borne relapsing fever – Borrelia recurrentis is the causative agent – Transmitted to humans by the human body louse – Endemic relapsing fever – Several Borrelia species can cause this disease – Transmitted to humans by soft ticks – Characterized by recurring episodes of septicemia and fever – Due to body’s repeated efforts to remove the spirochetes

• Borrelia – Relapsing fever – Observation of spirochetes is the primary method of diagnosis – Successful treatment is with antimicrobial drugs – Preventive measures – Avoidance of ticks and lice – Good personal hygiene – Use of repellent chemicals

• Leptospira 鉤端螺旋體 – Motile, obligately aerobic bacteria – Found in numerous wild and domestic animals – Leptospirosis – Caused by L. interrogans – Leptospira enters cuts/abrasions in skin and mucous membranes – Travels via the bloodstream throughout the body – Bacteremia eventually resolves – Eradication impractical due to the various animal reservoirs – Vaccine available for livestock and pets

• Vibrios – Share many characteristics with enteric bacteria – Found in water environments worldwide – Vibrio cholerae – Most common species to infect humans – Causes cholera – Humans infected by ingesting contaminated food and water – “Rice-water stool” is characteristic – Most important virulence factor is cholera toxin

• Vibrios – Diagnosis usually based on characteristic diarrhea – Treatment – Fluid and electrolyte replacement – Antimicrobial drugs are lost in the watery stool – Adequate sewage and water treatment can limit spread of V. cholerae

• Vibrios – Other diseases of Vibrio – V. parahaemolyticus 腸炎弧菌, 副溶血弧菌 – Results from ingestion of shellfish – Causes cholera-like gastroenteritis – V. vulnificus 海洋弧菌, 創傷弧菌 – Septicemia due to consumption of contaminated shellfish – Infections can result from washing wounds with contaminated seawater

• Campylobacter jejuni – Likely most common cause of gastroenteritis in the United States – Many animals serve as reservoirs for the bacteria – Humans infected by consuming contaminated food, milk, or water – Poultry is the most common source of infection – Infections produce self-limiting bloody and frequent diarrhea – Proper food handling and preparation can reduce spread of bacteria

• Helicobacter pylori – Slightly helical, motile bacterium that colonizes stomach of its hosts – Causes gastritis and most peptic ulcers – Produces numerous virulence factors that enable it to colonize the stomach

• Helicobacter pylori – Presence of H. pylori can be demonstrated by positive urease test – Biochemical tests provide a definitive identification – Treat with antimicrobial drugs in combination with drugs that inhibit acid production – Prevention – Good hygiene – Adequate sewage treatment – Proper food handling

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